在另一个 class 中调用实例变量

Question

我正在尝试访问实例变量 self.code in class Line in class Quote。我试图使以下规则通过：当报价同时包含 'door_sign' 和 'escape_sign' 行时，他们会收到整个报价的 10%。

这是代码。

class Client:
    def __init__(self, postcode):
        self.postcode = postcode


class Line:
    def __init__(self, code, unit_cost, quantity=1):
        self.code = code
        self.unit_cost = unit_cost
        self.quantity = quantity

    def cost(self):

        if self.code == 'door_sign' and self.quantity >=3:
            return self.unit_cost * self.quantity * 0.8
        else:
            return self.unit_cost * self.quantity

class Quote:
    def __init__(self, client=None, lines=[]):
        self.client = client
        self.lines = lines

    def cost(self):

**** 这是我的问题所在 ****

    for l in self.lines:
        if line.code == 'door_sign' and 'escape_sign':
            return sum([l.cost() * 0.9])
        else:
            return sum([l.cost()])

print('Rule')
assert Quote(client=Client(postcode=3000), lines=[
Line(code='escape_sign', unit_cost=20.0, quantity=10),
]).cost() == 200.0
assert Quote(client=Client(postcode=3000), lines=[
Line(code='door_sign', unit_cost=10.0, quantity=1),
Line(code='escape_sign', unit_cost=20.0, quantity=10),
]).cost() == 189.0

Answer 1

看起来你总是在打折，因为 escape_sign 总是 True 并且通过提前返回错误地计算成本。你为什么不在 def cost 方法中试试这个：

def cost(self):
    needed = {'door_sign', 'escape_sign'}
    discount = {l.code for l in self.lines} & needed == needed
    cost = sum(l.cost() for l in self.lines)
    return (cost * 0.9) if discount else cost

快速编辑，我错过了如果 escape_sign 和 door_sign 都在的话你想要折扣命令。

如果你想在一个循环中完成：

def cost(self):
    door = False
    escape = False
    cost = 0
    for line in self.lines:
        if line.code == 'escape_sign':
            escape = True
        elif line.code == 'door_sign':
            door = True
        cost += line.cost()
    return (cost * 0.9) if (escape and door) else cost

Answer 2

class Quote:
    def __init__(self, client=None, lines=[]):
        self.client = client
        self.lines = lines
    def cost(self):
        codes={l.code for l in self.lines}
        price_modifier = 0.9 if codes.issuperset({'door_sign','escape_sign'}) else 1.0
        return sum([l.cost()*price_modifier for l in self.lines])

在另一个 class 中调用实例变量

Calling an instance variable in another class

python

class

conditional

instance-variables